I was introduced to Soljanka by my landlady while I was living in Berlin - she was born and raised in East Berlin. She took me to a restaurant in Prenzlauerberg (a now-trendy neighborhood that is part of the former East Berlin) called Zum Schwesterjungen, which is apparently known for DDR specialties.

Anyway, it's delicious - sweet and sour and slightly spicy. Most of the recipes I'm finding on line are in German, which probably won't help you (unless you speak German?) but here's one from an American paper that sounds like it might be close to what I had:

The biggest difference I see is that the soup I had was made with speck instead of wurst, but a lot of the German recipes I'm seeing call for wurst or a mix of wurst and speck, so I assume both are authentic.

Solyanka may have become popular in the DDR following WWII, but it's definitely a Russian/Ukrainian, not German, soup. Any good Russian cookbook should have a recipe, see e.g. Anya von Bremzen, Anne Volokh, Darra Goldstein or Leslie Chamberlain.

Thanks for the tip, checked my Russian Cookbook and there it was...For whatever its worth, the book is "Cooking Russian in America"..For the truly bold cook it provides a recipe for 50 gallons of borsht!!!!